This invention relates to a stereoscopic photographic measuring device for calculating a three-dimensional position, a height or the like making use of a set of stereoscopic photographs (stereo photographs), and more particularly to a stereoscopic photographic measuring device wherein a stereoscope unit and two cursors are integrated with one another and constructed for movement at a time in two-dimensional directions in order that coordinate data or the like may be delivered readily to a data processing device.
Conventionally, a measuring device called precision patterning machine is required in order to find out three-dimensional coordinates from a set of stereoscopic photographs. The precision patterning machine is constituted such that a positive film is set on a drive table and a stereoscopic image is observed with rotation of a projector adjusted exactly in order to find out three-dimensional coordinates. However, such precision patterning machine is very expensive, and because a positive film is required in addition to the requirement for a skilled technique of operation, there is a problem that a common printed photograph cannot be used. In view of such problems of the precision patterning machine as described just above, a simple photographic measuring system has been developed which includes a digitizer, double cursors, a stereoscope unit and a small size calculator and wherein a stereoscopic photograph is observed in a stereoscopic vision to read plane coordinates of the photograph and the plane coordinates thus read are processed to calculate three-dimensional coordinates. (Japanese Utility Model Laid-Open No. 63-39618)
In the simple photographic measuring system, the reflecting stereoscope unit and the double cursors are formed as separate members and the reflecting stereoscope is supported on a movable arm while the double cursors are mounted for sliding movement on a support bar. Accordingly, the reflecting stereoscope unit and the double cursors have a construction wherein they can be moved freely on the digitizer, but they do not move in a mutually associated relationship but can change their positions independently of each other.
However, the conventional simple photographic measuring system described above does not have a construction wherein the reflecting stereoscope unit and the double cursors do not move in a mutually associated relationship. Accordingly, when a measuring operation is to be performed, at first the reflecting stereoscope unit is positioned at a position corresponding to a point of measurement, and then, while looking through the reflecting stereoscope unit at the position, relative positions of a set of stereoscopic photographs are moved to adjust such that a stereoscopic vision may be attained. Further, an index of one of the cursors must be adjusted to the point of measurement and an index of the other cursor must be made coincide with the index of the one cursor. When a stereoscopic photographic measurement is to be performed, normally a data processing for a large number of points of measurement is required, and with the photographic measuring system, such a measuring operation as described above must be repeated for each reading of data. A repetition of such operations not only deteriorates the operation efficiency remarkably but also makes a cause of an error in measurement. Further, when altitude differences or contour lines are to be produced from a stereoscopic photograph, there is no necessity of reading coordinates but there is the necessity of reading a distance between the two cursors. However, while the stereoscopic photographic measuring system of the conventional type described above includes a mechanism for adjusting the distance between the two cursors, it does not include a device for electrically measuring such distance. Therefore, the distance between the two cursors must necessarily be measured by visual observation of an operator. Accordingly, the conventional stereoscopic photographic measuring system has drawbacks that the operation efficiently is low and that an error in measurement or the like is brought about.